The prime objective of the center grant proposal is to provide core facilities for morphological, biochemical and physiological studies of the visual system. The research encompassed in the proposal deals with cellular mechanisms in the visual process. The main emphasis in all these studies is on the structure and function of single neurons and on the interaction between cells at various levels in the visual pathway. Analysis of receptive field properties of single cells and the functional architecture of the mammalian visual pathways are central problems in the proposal. Single cell studies will be complemented by the use of various anatomical techniques, including new tracer methods already employed successfully. The synaptic morphology at various levels in the visual pathway will be studied using light and electron microscopic techniques. Anatomical and physiological studies will be done in monkeys, cats and mice raised under various conditions of visual deprivation to learn about the relative role of innate and environmental influences during development. The availability of mammalian visual mutants makes it possible to study the nature of neuronal specificity and related developmental problems. The response properties of single photoreceptors and the synaptic transmission to second order neurons will be analyzed in vertebrate and invertebrate retinas. The identity and localization of neurotransmitters will be studied in the intact retina and in vitro, using isolated and identified single retinal neurons.